This invention relates to a glass plate having on one side thereof a reflective multilayer coating, which includes a TiN layer, in order that the glass plate should assume a golden appearance at least when viewed from the opposite side. The coated glass plate is useful, for example, as a building material or an ornamental material.
Glass plates are often coated with a metal or metal compound for light or heat reflecting purposes and also for coloring purposes. To afford a golden appearance to a glass plate the simplest method is providing a coating film of Au, but this method is very costly. A long known substitute is a multilayer coating using Ag and Cu, but this coating is not very satisfactory in its hue and durability.
It is known that golden appearance can be afforded to a glass plate by using TiN as a coating material. However, TiN coating films on glass plates are significantly variable in color according to the coating method and coating conditions. For example, JP No. 47-14820 which relates to solar radiation reflcting glass plates gives an example wherein a TiN coating film deposited by high-frequency sputtering assumed a greenish color by reflection. Besides, it is not easy to provide a glass plate with a TiN coating film of good quality particularly in respect of adhesion strength and durability. According to JP-A No. 60-43481, an improved TiN coating film of a golden hue can be formed on a glass plate by using a special sputtering method characterized by passing the sputtered particles through a high-frequency plasma thereby exciting particles. However, this method entails a special sputtering apparatus and complicated operations and, nevertheless, the coating film may not satisfactory in durability. According to JP-A No. 60-187671, a two-layer coating made up of an inner layer of TiO.sub.2 and an outer layer of TiN or a three-layer coating including another TiO.sub.2 layer on the TiN layer is formed on a glass plate by carrying out sequential reactive sputtering in a vacuum chamber containing at least two targets of titanium for forming the inner TiO.sub.2 layer and the TiN layer, respectively, and a mixed gas of argon, oxygen and nitrogen. This method is very complicated.